Several lines of clinical evidence suggest that steroid hormones play an influential role in the biological behavior of benign nevi and human melanoma. Early work in our laboratory suggests that estrogen may exert a biological effect on benign nevi in its pathophysiological transformation to its malignant counterpart--melanoma. There is also experimental evidence from our laboratory suggesting a possible role of estrogen and progesterone on human melanoma in vitro and in vivo (using athymic mice). The specific aim of this study is to evaluate the effect of estrogen on benign nevi, identification of estrogen receptors containing the subpopulation of melanoma patients and its clinical correlation of biological behavior of melanoma to the receptor status, and effect of estrogen and progesterone on the growth and spread of human melanoma growth in athymic mice. It is expected that information obtained from the above study will be extremely valuable in understanding the biology of human melanoma. This information will also enable us to determine if hormonal manipulation can be used in the therapy of disseminate melanoma.